Fire protection system

ABSTRACT

A system for protecting a structure and its contents from fire wherein a plurality of extinguishant discharge heads are disposed in the space defined by the structure, with each head being responsible for a particular portion of said space. A fire responsive device is automatically responsive to a predetermined temperature existing in one or more portions of the space at a distance of less than six inches from the ceiling of the structure, for actuating the head responsible for the space and causing a resultant discharge of extinguishant from the head.

United States Patent 1191 Livingston [451 July 3,1973

[ FIRE PROTECTION SYSTEM William L. Livingston, Sharon, Mass.

[73] Assignee: Factory Mutual Research Corporation, Norwood, Mass.

[22] Filed: Apr. 26, 1971 [21] Appl. No.: 137,336

[75] Inventor:

[52] U.S. Cl. 169/16, 169/37 [51] Int. Cl. A62c 32/12 [58] Field ofSearch 169/5, 16, 42, 17, 169/37 [56] References Cited UNITED STATESPATENTS 3,454,097 7/1969 Groos 169/42 X 3,393,746 7/1968 Hodnett 169/42X 3,590,924 7/1971 Emmons et al..... l69/l7 l,522,704 l/l925 Salmon,.lr.169/37 X Primary Examiner--M. Henson Wood, Jr. Assistant ExaminerMichaelMar Attorney-Lane, Aitken, Dunner & Ziems 5 7] ABSTRACT A system forprotecting a structure and its contents from fire wherein a plurality ofextinguishant discharge heads are disposed in the space defined by thestructure, with each head being responsible for a particular portion ofsaid space. A fire responsive device is automatically responsive to apredetermined temperature existing in one or more portions of the spaceat a distance of less than six inches from the ceiling of the structure,for actuating the head responsible for the space and causing a resultantdischarge of extinguishant from the head.

1 Claim, 3 Drawing Figures PATENIEDJUL3 ma 3,7

SHEU 1 0F 3 k I Y 5 if INVENTOR WILLIAM L. LIVINGSTON ATTORNEYSPATENIEDJULSI ms 3.743.022 sum 2 or 3 INVENTOR WILLIAM L. LIVINGSTONATTORNEYS PAIENIEBJuLB ms 3.743.022 saw-*3 or 3.

INVENTOR WILLIAM L. LIVINGSTON ATTORNEYS FIRE PROTECTION SYSTEMBACKGROUND OF THE INVENTION This invention relates to a fire protectionsystem, and more particularly to such a system utilizing criticalspacing of the discharge heads with respect to the ceiling of thestructure to be protected, with" each head being adapted to be actuatedin response to a relatively high temperature.

There are numerous fixed fire extinguishing systems in existence todayin which a plurality of sprinkler heads are mounted at a fixed relationfrom the ceiling of the structure to be protected from fire. Eachsprinkler head is usually actuated by a thermal fuse element which isadapted to fuse and cause the discharge of extinguishant against adeflector disc to create a mist-like spray pattern. The great majorityof these systems dispose their sprinkler heads in a manner whereby thethermal fuse elements extend a distance from 6 to 18 inches from theceiling of the structure. Also, the thermal fuse elements are usuallyadapted to fuse at a temperature slightly less than 300 F., with atemperature of 285 F. being common.

It has been discovered that, upon a fire of a large magnitude occurringin the space to be protected by a prior art system of the above type,too many of the sprinkler heads are often actuated. This results in arelatively inefficient operation, since a sprinkler head located at arelatively long distance from the fireball, but yet close enough to beactuated due to the high temperatures occurring throughout a largeportion of the space, robs a sprinkler head extending directly over thefireball from valuable extinguishant and extinguishant pressure.

SUMMARY OF THE INVENTION It is therefore an object of the invention toprovide a fixed fire extinguishing system in which the heads are morediscriminatory in nature, i.e., only the heads located at criticalportions relative to the fire are actuated, while heads more removedfrom the fire are maintained in a deactivated state.

It is a further object of the present invention to provide a fixed fireextinguishing system in which the heads located in the immediatevicinity of a fireball occurring in the structure to be protected, areactuated in a relatively short time.

;Towards the fulfillment of these and other objects, the system of thepresent invention comprises a plurality of extinguishant discharge headslocated in the space defined by the structure to be protected, each headbeing responsible for a particular portion of said space, means fordelivering extinguishant from a source of supply to each of said heads,and fire responsive means automatically responsive to a predeterminedtemperature existing in one or more portions of said space at a distanceof less than six inches from the ceiling of said structure for actuatingthe head responsible for said portion. The above-mentioned predeterminedtemperature is at least 500 F.

BRIEF DESCRIPTION OF THE DRAWINGS Reference is now made to theaccompanying drawings for a better understanding of the nature andobjects of the present invention. The drawings illustrate the best modepresently contemplated for carrying out the objects of the invention,and are not to be con- DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1of the drawings depicts a building shown in general by the referencenumeral 10 and employing a fixed fire extinguishing system of the priorart. In particular, the building 10 has a floor 12 and a ceiling 14,with the side walls of the building being cut away for convenience ofpresentation.

A fuel array is disposed in the building, and for the purposes ofexample is shown in the form of a plurality of stacked cartons referredto in general by the reference numeral 16.

The fixed fire extinguishing system of the prior art is shown mounted inthe building 10 and includes a plurality of sprinkler heads 20, 22, 24,and 26 depending from a plurality of branch lines 28, 30, 32, and 34,respectively, extending perpendicular to, and registering with, asub-main 36. The branch lines 28, 30, 32, and 34 are spaced atapproximately fifteen foot' intervals along the sub-main 36 and,although not shown in the drawings, it is understood that an additionalnumber of sprinkler heads are spaced along each branch line at the sameinterval. It is also understood that the branch lines 28, 30, 32, and34, and the sub-main 36, are fastened relative to the ceiling l4, andthat a source of extinguishant, such as a water main, is connected tothe sub-main 36 by means of risers, etc., all in accordance withconventional practice.

The sprinkler heads are of the conventional type normally utilized insystems of this kind and, as described above, include a deflector discat their free ends for creating a mist-like spray of extinguishant.Also, a plurality of thermal fuse elements 20a, 22a, 24a, and 26a aremounted on the sprinkler heads 20, 22, 24, and 26, respectively, and areadapted to fuse in response to a predetermined selected temperature topermit the discharge of extinguishant from said heads, against thedeflector discs, and towards the cartons 16.

As indicated earlier, the great majority of the prior art fixed fireextinguishing systems of this nature locate their piping systems andsprinkler heads in such a manner that the thermal fuse elements extend adistance from 6 to 18 inches from the ceiling of the building. Also inaccordance with traditional fire fighting practice, each thermal fuseelement is designed to fuse, and therefore actuate its sprinkler head,at a temperature of slightly less than 300 R, such as, for example, 285F.

In accordance with this prior art arrangement, upon a fireball 38developing in the building 10 as a result of the ignition of a portionof the stacked cartons 16, the instantaneous temperature gradients canbe typified by the temperature values shown adjacent each of the heads20, 22, 24, and 26 in FIG. 1. In particular, it has been discovered thatwith a fireball temperature of approximately 2,500 F., the temperatureof the head 20 immediately above the fireball typically takes a value ofapproximately 2,300 F. Also, the temperature at the head 22 isapproximately 900 F., the temperature at the head 24 is approximately350 F., while the temperature at the head 26 is approximately 300 F.

It can be appreciated that, as a result of the above temperaturegradient, the heads 20, 22, 24, and 26 will all be actuated in responseto their respective thermal fuse elements being fused, due to the factthat each of the temperatures in the immediate vicinity of the latterheads exceeds 285 F. The actuation of the heads 24 and 26 isundesirable, since they are respectively located approximately 30 feetand 45 feet from the head and therefore add very little to the firefighting capability of the system. Thus, the actuation of the heads 24and 26 may very well rob the heads 20 and 22, which are locatedimmediately over the fire and a distance of fifteen feet therefrom,respectively, from valuable extinguishant, and, in addition, reduce theextinguishant pressure available to the latter heads.

As a further disadvantage of this prior art arrangement, there is arelatively large difference between the temperature of 900 F. occurringin the vicinity of the head 22, and the temperature of 2300" F.occurring in the vicinity of the head 20. As a result, there is arelatively long delay between actuation of the head 20 and the head 22.This delayed response of the head 22 may also curtail the fire fightingcapability of the system.

It is noted that, as a result of the fireball 38, the gaseous productsof combustion travel upwardly from the fireball by convection, impingeagainst the ceiling 14, and move radially outwardly along the ceiling.These combustion gases, along with air that is entrained in theirmovement, form a layer extending from the ceiling 14 for a distance ofbetween 1 to 6 inches and shown in general by the reference numeral 39.The sig nificance of this layer 39 will be described in detail later, itbeing sufficient to note for the purposes of the prior art arrangementof FIG. 1, that the heads 20, 22, 24, and 26 extend below the layer.

The fixed fire extinguishing system of the present invention is designedto overcome the above deficiencies, and is shown in FIG. 2 in the sametype building as depicted in FIG. 1, with identical structure beinggiven identical reference numerals.

In particular, the system of the present invention employs a pluralityof direct discharge heads 40, 42, 44, and 46 mounted relative to theceiling l4, and having thermal responsive devices 40a, 42a, 44a, and46a, respectively, connected thereto, with the details of a head and itsthermal responsive device being described later.

In accordance with the present invention, the heads 40, 42, 44, and 46are mounted closer to the ceiling 14 of the structure than in the priorart systems. In particular, the branch lines 28, 30, 32, and 34, as wellas the sub-main 36, are located in a manner relative to the ceiling 14so that the thermal responsive devices 40a, 42a, 44a, and 46a are spaceda distance of less than six inches from the ceiling. Also, the thermalresponsive devices 40a, 42a, 44a, and 46a are adapted to respond to ahigher temperature than that of the thermal fuse element of the priorart system, which higher temperature is preferably at least 500 F.

As discussed above, the fireball 38 creates the gaseous products ofcombustion which travel upwardly from the fireball by convection,impinge against the ceiling l4, and move radially outwardly along theceiling, and, together with the air that is entrained, form a layer 39extending from the ceiling 14 for a distance of between I to 6 inches.

As shown in FIG. 2, the thermal responsive devices 40a, 42a, 44a, and46a are located within the layer 39. This specific positioning is madeas a result of the applicant having discovered that a more definable anddramatic temperature gradient exists in the layer 39 than in therelatively cold area extending below this area in which thecorresponding heads of the prior art system are located.

As an example of the above-mentioned temperature gradient in the layer39, the approximate temperatures in the immediate vicinity of the heads40, 42, 44, and 46 are shown in FIG. 2. In particular, the approximatetemperature in the immediate vicinity of the head 40 is 2,300 E, in thevicinity of the head 42 is 1,300 E, in the vicinity of the head 44 is450 F., and in the vicinity of the head 46 is 400 F.

As a result of the above temperatures and the fact that the thermalresponsive devices 40a, 42a, 44a, and 46a are adapted to actuate theirrespective heads at a temperaure of at least 500 F., the heads 40 and 42will be actuated, while the heads 44 and 46 will not be actuated. Sincethe latter heads are located a distance of 30 feet and feet,respectively, from the nozzle 40, and therefore would be of little helpin extinguishing the fireball 38, it is highly desirable that they notbe actuated under the conditions shown, since, if actuated, they wouldrob the heads 40 and 42 of valuable extinguishant and extinguishantpressure.

It is also noted that the difference between the temperature in thevicinity of the head 40 and the head 42 is not as great as thetemperature difference between the corresponding heads 20 and 22 of theprior art systern. As a result, the time lag between actuation of thehead 40 and the head 42 is reduced considerably, which further improvesthe fire fighting capability of the system.

The details of the discharge head 40 used in the arrangement of FIG. 2are shown in FIG. 3, it being understood that the remaining headsutilized in the system of the present invention are constructed in anidentical manner. The head 40 comprises a cylindrical body 52 having anupper end portion which is internally threaded as shown at 54 forconnection to a source of extinguishant such as water, and a lower endportion which defines an outlet orifice 56 of a reduced crosssection. Apair of spiral vanes 58a and 58b are fixed within the body 52 forimparting a swirling motion to water flowing downwardly therethrough ina conventional manner. The vanes 58a and 58b support a hollow centralhub 60 which, in turn, slidably supports a rod 62 having a head 64 fixedon its lower end. A pair of O-ring seals 66 and 68 extend between thehead 64 and the inner wall of the body member 52, with the head servingto block the outlet orifice 56 as will be described in detail later.

The rod 62 is latched in the position shown in FIG. 3 by the thermalresponsive device 40a. This device includes a rod 72 which slidablyextends through an externally threaded boss 74 projecting from the sideof the body 52. One end of the rod 72 extends through the vane 58a andthe wall of the central hub 60 into a slot 76 in the rod 62 to latch itin the position shown in FIG. 3.

A sleeve 78 is threaded on the end of the boss 74. The outer end of thesleeve 78 is closed off by an externally threaded stub shaft 80 having aring or yoke 82 thereon. The rod 72 slidably extends through the stubshaft 80, and the other end of the rod engages a conventional thermalfuse element 84 positioned within the ring 82. The fuse element 84prevents movement of the rod 72 to the right as viewed in FIG. 3, untilthe heat of a fire fuses the element so that it collapses. Since thefuse element 84 is the standard type commonly used in conventionalsprinkler heads now on the market, it will not be described in greaterdetail.

The rod 72 has a piston head 86 mounted thereon which slidably engagesthe internal wall of the sleeve 78. A spring 88 is positioned betweenthe boss 74 and the piston head 86 to bias the piston head and the rod72 to the right with a predetermined biasing force.

With this arrangement, the piston head 86 and the rod 72 will be drivento the right under the action of the spring 88 upon the fuse element 84collapsing in response to the temperature in the immediate vicinity ofthe fuse element 84 exceeding 500 F. This unlatches the rod 62 andallows it, along with the head 64, to be expelled from the outletorifice 56 of the body 52, and permit the water to spray out through theorifice.

It can be appreciated that the head spacing and the temperaturesdiscussed in connection with the system of FIG. 1 and the system of FIG.2, are based on specific test conditions which, if varied, may causecorresponding variations in the head spacing and actuation temperaturesset forth.

Of course, other variations of the specific construction and arrangementof the fixed fire extinguishing system disclosed above can be made bythose skilled in the art without departing from the invention as definedin the appended claims.

I claim:

l. A system for protecting an enclosed structure having a ceiling fromfire, comprising a plurality of heads located in said structure fordischarging extinguishant directly towards said fire, each head beingresponsible for a particular portion of said space, means for deliveringextinguishant from a source of supply to each of said heads, a thermalfuse member associated with each head and located less than six inchesfrom said ceiling so that at least a portion of said fuse members willbe directly exposed to the layer of hot gases that move in a generallyhorizontal direction along said ceiling as a result of a fire occurringat a random location in said structure, each thermal fuse member beingadapted to fuse at a temperature of at least 500F. so that the fusemembers located generally over said fire will be fused while the fusemembers spaced a predetermined horizontal distance from said fire willnot be fused, and means associated with each of said heads for normallypreventing the discharge of extinguishant from said heads, said lattermeans being responsive to said fusing of said thermal fuse members forpermitting the discharge of extinguishant from their respective heads.

1. A system for protecting an enclosed structure having a ceiling fromfire, comprising a plurality of heads located in said structure fordischarging extinguishant directly towards said fire, each head beingresponsible for a particular portion of said space, means for deliveringextinguishant from a source of supply to each of said heads, a thermalfuse member associated with each head and located less than six inchesfrom said ceiling so that at least a portion of said fuse members willbe directly exposed to the layer of hot gases that move in a generallyhorizontal direction along said ceiling as a result of a fire occurringat a random location in said structure, each thermal fuse member beingadapted to fuse at a temperature of at least 500*F. so that the fusemembers located generally over said fire will be fused while the fusemembers spaced a predetermined horizontal distance from said fire willnot be fused, and means associated with each of said heads for normallypreventing the discharge of extinguishant from said heads, said lattermeans being responsive to said fusing of said thermal fuse members forpermitting the discharge of extinguishant from their respective heads.